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The Ultimate Guide to Caulk and Sealants

The Ultimate Guide to Caulk and Sealants

The Ultimate Guide to Choosing the Right Caulk or Sealant 


Choosing the right caulk or sealant is fundamental for a successful project. The three main types of sealant are Polyurethane Sealants, Hybrid or SMP Sealants and MS Polymer Sealants. All three types of sealants are slow curing, moisture cure products. This handy guide takes you through the similarities and differences of your sealant options to help you achieve the best results for your needs! 


Chemique Adhesives comprehensive range of industrial strength sealants provides versatility across a variety of industries including aerospace, automotive, commercial manufacturing, composites, construction, furniture, marine, transportation and more!


How To Choose The Right Sealant

Things To Consider...

Keep reading to find out 6 different tips to consider when deciding which type of sealant is ideal for your project…


#1: Where will you use your sealant? 

The first step when deciding about what type of sealant or caulk to use, is to think about where your sealant will be used. The type of project you are undertaking will determine the best sealant option...

Polyurethane sealants are great for indoor and outdoor applications and work as great structural sealants in the construction industry. Any mechanical projects or automotive building and repair that require strong adhesion, these sealants are a great option as their adhesion strength is much higher than traditional silicone sealants and they don't degrade over time!
Hybrid (SMP) sealants are ideal for bonding glass in all vehicle types, structural bonding and sealing, door and window construction. The versatile range can be used to bond a huge range of substrates including rubber, membrane roofing and playground flooring, as well as various construction materials such as natural stone, ceramic, wood, metals and plastics. 
MS polymer sealants are known for their fantastic applications in marine environments such as yacht manufacturing and boat making, and even in specialty vehicle manufacturing. This is due to their polymer technology that provides water-tight sealing of joints. Choosing this sealant is a fantastic option for any projects with water exposure such as bathroom restoration or boat maintenance as they are                                    paintable, have incredible UV resistance and are lasting in salted water conditions.

#2: What color do you want your sealant?

Another important factor to consider is where you are using the caulk. If the sealant is visible, for use in the bathroom for example, then you may prefer a white sealant. For many caulking jobs, it is most important that it is not noticeable. All three types of sealants are available in white, as well as gray and black. Alternatively, for other projects you may refer a clear sealant which is available in silane modified polyurethane sealants, as well as green and beige. Additionally MS polymer sealants are also available in mahogany and teal, perfect for marine projects.


#3: Solvents and hazards

Both silane modified polyurethane sealants and MS polymer sealants are great solvent free options. Isocyanates are highly reactive chemicals. The reaction to moisture releases carbon dioxide molecules which can form bubbles that reduce the final strength of the sealant. Polyurethane sealants do contain isocyanates, whereas silane modified polyurethane sealants and MS polymer sealants are hazard free!


#4: How much water resistance is needed?

Both silane modified polyurethane sealants and MS polymer sealants can be used and applied to wet surfaces. Additionally they can be overpainted when wet. This provides a useful option for outdoor projects and bathroom or kitchen applications.


#5: Is the sealant exposed to excessive sunlight?

If the area where you will be applying the sealant will be exposed to consistent sunlight, such as around the windows of RVs, you will want to consider using a sealant that is UV stable. Both the silane modified polyurethane sealants and MS polymer sealants offer UV stability, preserving the brilliant color of your sealant.


#6: Viscosity types

Silane modified polyurethane sealants and MS polymer sealants are both available in low and high viscosity grades, whereas polyurethane sealants are available as a high viscosity product.


Polyurethane Sealants (PU)

Polyurethane sealants or PU sealants are generally a slow cure, high viscosity moisture cure sealant. They are based on technology utilizing organic material, and are well known for their high performance bonding and sealing properties in both indoor and outdoor environments.

Mechanical and adhesion strength are often much higher than traditional silicone sealants, and its properties can be tailored for nearly any use. Due to polyurethane sealants’ hardness, adhesion strength, thixotropy, and flexible performance, they have been used for decades in the construction, automotive, truck building and RV manufacturing industries. Polyurethane sealants and relied on for their strength, durability and flexibility and are a great option for these industries as they do not degrade over time! It is important to keep in mind however, that polyurethane sealants contain isocyanates and cannot be overpainted when wet or applied to wet surfaces.



Hybrid Sealants (SMP)


Silane modified polyurethane sealants are generally known as hybrid sealants, giving polyurethane strength combined with the flexibility you get from silicones. They are part of a new generation of isocyanate-free, high strength bonding and sealing technology. These polyurethane based sealants use a modified silane polymer as its chemical base, which is known for offering superior adhesion and green strength when compared to traditional silicone based adhesives and sealants. 



MS Polymer Sealants


These fantastic sealants were originally developed in Japan as a very flexible, strong construction sealant that was able to handle Japan’s frequent earthquakes. MS polymer sealants have evolved into a diverse performance-driven range, offering superior sealing and bonding solutions covering many industries. There are many benefits to using MS polymers include their solvent and isocyanate free formulations, strong yet flexible bonds while sealing lines, odorless formulation, and ability to be painted wet on wet, as well as incredible UV resistance. MS polymer adhesives have a broad range of applications including structural sealing, marine environments such as yacht manufacturing and boat making, and even specialty vehicle manufacturing.



To Sum it All Up...

Have a look at this handy overview that gives you a quick guide to choosing the right sealants for your projects!

Polyurethane Sealants

  • Generally, a slow cure high viscosity moisture cure PU (MCPU) sealant
  • Contains Isocyanates and may have hazard warnings
  • Not UV stable
  • Cannot be overpainted when wet
  • Cannot be applied to wet surfaces
  • Only available as a high viscosity product
  • Black, gray and white

Silane Modified Polyurethane Sealants    

  • Known generally as hybrid sealants
  • Free of isocyanates
  • Solvent Free
  • Can be overpainted when wet
  • Can be applied to wet surfaces or under water
  • UV Stable
  • Available in low and high viscosity grades
  • Black, gray, green, beige, clear and white


MS Polymer Sealants

  • Free of isocyanates
  • Solvent free
  • No hazards
  • Can be overpainted when wet
  • Can be applied to wet surfaces
  • UV stable
  • Available in low and high viscosity grades
  • Marine approved, good for below the water line
  • Grades for glass installations, marine and automotive
  • Black, gray, mahogany, teal and white



Shop our wide selection of industrial-grade sealants today to complete your next project.
For more information visit or click here to browse all sealants and caulks!


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